Compensating for degradation of electronics due to radiation vulnerable components

ABSTRACT

Techniques to compensate non-radiation hardened components for changes in performance that result from exposure to radiation. The techniques of this disclosure apply a predetermined bias signal to a representative non-radiation hardened component while a system is in use. The system determines whether there is a performance change in characteristics, such as voltage response, frequency response, gain, or other characteristics. The system may determine a compensation factor that may restore the desired signal output from the component. The system may compensate a second identical component that is in use in the system with the compensation factor. The component receiving the predetermined bias signal acts as a characterization dosimeter of the component in use in the system. A number of radiation vulnerable components may be characterized simultaneously with exact representative parts. The system may compensate identical component in use in the system with the appropriate compensation factor for each.

TECHNICAL FIELD

The disclosure relates to circuits exposed to radiation.

BACKGROUND

Degradation of performance or operation of electronic systems occurs inradiation environments due to component radiation vulnerability. In manycases, components are still operational, but their performancecharacteristics will change as a result of radiation exposure. Currentmethods include using radiation hardened components. Radiation hardenedcomponents are not available for some component types and also tend tohave long lead times and be significantly more expensive.

SUMMARY

In general, the disclosure is directed to techniques to compensatenon-radiation hardened components for changes or degradation inperformance that result from exposure to radiation. The techniques ofthis disclosure include applying a predetermined bias signal to anon-radiation hardened component while a system is in use. The systemdetermines whether there is a performance change in characteristics ofthe component. Some examples of component performance characteristicsmay include voltage response, frequency response, gain, leakage or othercharacteristics. The system may determine a compensation factor that mayrestore the desired signal output from the component. The system maycompensate a second identical component that is in use in the systemwith the compensation factor. The component receiving the predeterminedbias signal essentially acts as a characterization dosimeter of thecomponent in use in the system.

The system may include multiple vulnerable, non-radiation hardenedcomponent types placed throughout a system supplied with predeterminedbias signal. The outputs of the biased components may be fed to ananalog switch that may further sends the received signals to ananalog-to-digital (A/D) converter or other monitoring circuit. In thismanner, a large number of radiation vulnerable components to becharacterized simultaneously with exact representative parts. The systemmay compensate identical component in use in the system with theappropriate compensation factor for each.

In one example, the disclosure is directed to a circuit comprising: afirst component of a first type, wherein the first component isconfigured to receive a bias signal and output a first output signal, asecond component of the first type, and a processing circuit. Theprocessing circuit is configured to: receive the first output signal,determine that there is a performance change in the first component overa period of time based on the first output signal, in response todetermining that there is performance change in the first component,determine a compensation factor, wherein the compensation factor isconfigured to compensate the output of the first component based on theperformance change, compensate a second output signal from the secondcircuit component based on the compensation factor.

In another example, the disclosure is directed to a method comprising:biasing a first component of a first type with a predetermined biassignal, determining, by a processor circuit, a first output signal ofthe first component, comparing, by the processor circuit, the firstoutput signal to an expected signal of the first component based on thepredetermined bias signal. Based on a difference between the firstoutput signal and the expected signal, compensating a second outputsignal from a second component of the first type.

The details of one or more examples of the disclosure are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the disclosure will be apparent from thedescription and drawings, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an example system configured tocompensate a non-radiation hardened component based on biasing arepresentative component, according to one or more techniques of thisdisclosure.

FIG. 2 is a block diagram illustrating an example system configured tocompensate a non-radiation hardened component based on characterizationof similar components, according to one or more techniques of thisdisclosure.

FIG. 3 is a block diagram illustrating an example circuit that maycompensate the input of a circuit component to achieve a desired outputsignal.

FIG. 4 is a block diagram illustrating an example circuit that maycompensate the signal from a non-radiation hardened circuit component tocorrect for performance changes from radiation, according to one or moretechniques of this disclosure.

FIG. 5 is a block diagram illustrating an example circuit that maycompensate a downstream component to correct for performance changesfrom radiation, according to one or more techniques of this disclosure.

FIG. 6 is a flow chart illustrating an example mode of operation of acircuit configured to compensate one or more non-radiation hardenedcomponents for the effects of radiation, according to one or moretechniques of this disclosure.

FIG. 7 is a flow chart illustrating an example mode of operation of acircuit configured to compensate one or more non-radiation hardenedcomponents based on calibration data of the effects of radiation,according to one or more techniques of this disclosure.

DETAILED DESCRIPTION

In general, the disclosure is directed to techniques to compensatenon-radiation hardened components for changes or degradation inperformance that result from exposure to radiation. There are severaltechniques to determine the needed compensation.

In some examples, a sample of components to be used in a system may beexposed to a known amount of radiation over a predetermined time periodduring a testing or modeling phase. Testing and modeling may includetime-dependent effects associated with total dose radiation exposure,both dose rate (flux) and time-dependent effects (TDE) mechanisms, suchas annealing, and correlated with temperature dependencies. Thecomponent's performance characteristics, such as voltage response,frequency response, gain, leakage or other characteristics, may bemeasured at various exposure levels to the radiation to model acomponent's performance as a function of the exposure to radiation. Insome examples, some performance characteristics may change as thecomponent's exposure to an amount of radiation increases. During normaloperation, a system may include one or more devices, such as a radiationdosimeter, that measure the amount of radiation to which the system hasbeen subjected. The system may compensate the non-radiation hardenedcomponent based on the amount of radiation received and the knowncomponent performance change caused by radiation as determined duringthe modeling of the sample components.

In one example, a system may include a metal oxide semiconductor fieldeffect transistor (MOSFET) dosimeter for measuring the radiation. Thechange in performance as a result of radiation exposure to thevulnerable, non-radiation hardened component part may be characterizedand available to the system. In some examples, the radiationcharacterization may be saved in system memory as a lookup table, or asone or more linear or non-linear formulae. The system may determine acompensation factor that may restore the desired signal output from thecomponent. The system may apply the compensation via summing amps,digital to analog electronics, or other methods. Other examples ofcompensation may include using additional parts to correct the output ofthe sensitive part or by re-interpreting the output to compensate forthe radiation response of the part as characterized.

In another example, to determine compensation, a system may beconfigured to apply a known or constant bias signal to a non-radiationhardened component while the system is in use. The system determineswhether there is a performance change in characteristics of thecomponent by monitoring an output of the component while the componentis subject to the bias signal. Some examples of component performancecharacteristics, may include voltage response, frequency response, gain,leakage or other characteristics. The system may determine acompensation factor that may restore an output of the component to anoriginal value. The system may compensate a second component that is inuse in the system using the compensation factor determined for thecomponent subject to the bias signal. Thus, the component receiving theknown bias signal may essentially act as a characterization dosimeter ofthe component in use in the system.

The system may include multiple vulnerable, non-radiation hardenedcomponent types placed throughout a system supplied with predeterminedbias signals. The outputs of the biased components may be fed to ananalog switch that may further send the received signals to an analog todigital (A/D) converter or other monitoring circuit. In this manner, alarge number of radiation vulnerable components may be characterizedsimultaneously with representative parts, that is components behave thesame when exposed to radiation. The system may compensate components inuse in the system with the appropriate compensation factor for each.

The techniques of this disclosure may allow some components that haveknown radiation vulnerability to be used in applications that currentlyrequire radiation hardened components. Radiation hardened systems,comprised completely of radiation hardened components, typically cost agreat deal more than systems without radiation hardened components. Insome examples, completely unique designs need to be created to only useavailable radiation hardened components and may be limited bynon-availability of a radiation hardened version of a desired component.The limited selection may mean some designs may not be able to takeadvantage of components that do not have a radiation hardened version.This may result in limiting a design to slower, less capable components,or in reducing features that may be useful because a component is notavailable as radiation hardened. Other limitations may include size andweight. Limiting a design to radiation hardened components may result innot taking advantage of smaller components with the same or betterperformance characteristics. The techniques of this disclosure may allowcomponents with lower radiation tolerance to be used without theresulting longer lead time and greater expense. The techniques of thisdisclosure may open numerous opportunities for creation of much lessexpensive systems, or in some cases, new systems that currently cannotbe designed or created at all because of radiation environments.

FIG. 1 is a block diagram illustrating an example system configured tocompensate a non-radiation hardened component based on biasing arepresentative component, according to one or more techniques of thisdisclosure. The example of system 100 is shown as an aerospaceapplication, but the techniques may be applied to any potentialenvironment subject to radiation exposure, such as medical, power plantsand similar environments.

FIG. 1 includes a spacecraft 112 that includes a circuit 120 and may besubject to radiation exposure 15. Radiation exposure 15 may include anytype of radiation including alpha, beta, gamma, X-ray and the like.

Circuit 120 may perform any number of possible functions. In the exampleof spacecraft 112, circuit 120 may perform communications, datagathering, navigation, power conversion or any other function performedby a circuit. The example of circuit 120 includes processing circuit 122connected to memory 124, as well as signal generation circuit 130,monitoring circuit 136 and circuit component 128. Signal generationcircuit 130 may output one or more bias signals to biased component 126.In some examples circuit 120 may include sensing circuit 34 that mayreceive signals from one or more sensors 132.

The techniques of this disclosure may be advantageous to compensateanalog components and analog signals, though the techniques may also beapplied to digital or combination analog/digital circuits. Forsimplicity, the description will focus on compensating analogcomponents, therefore, unless otherwise noted, circuit component 128 andbiased component 126 may be assumed to be analog components, such as anamplifier, which may include one or more subcomponents, such astransistors, resistors, capacitors and other similar subcomponents.Other examples of biased components may be, but are not limited to, ringlaser gyros, accelerometers, integrated circuits, operationalamplifiers, Zener diodes, analog to digital converters, and voltagereferences.

Processing circuit 122 may perform one or more functions for circuit120. For example, processing circuit 122 may be configured to receive anoutput signal 44 from biased component 126 via monitoring circuit 136.In some examples, monitoring circuit 136 may be included withinprocessing circuit 122. Processing circuit 122 may determine whetherthere is a performance change over time in biased component 126, basedon output signal 44. In response to determining that there isperformance change in biased component 126, processing circuit 122 maydetermine a compensation factor, such that the compensation factor isconfigured to restore the desired signal output from biased component126. In other words, the compensation factor, when applied to outputsignal 44, may correct output signal 44 to a desired or original signalthat biased component 126 may have output before the performance ofbiased component 126 changed. The compensation factor may compensateoutput 44 of the biased component 126 based on the performance change.In some examples, the compensation factor be a scaling factor, an offsetfactor or some combination of both. The compensation factor may impactany one of the performance characteristics of biased component 126, suchas voltage response, frequency response, gain, leakage and othercharacteristics. In the example of an amplifier, the impact on voltageresponse may include dampening overshoot, restoring the response speed,and increasing or decreasing the amplification as need. In the exampleof a filter, the compensation factor may impact the 3 dB point in thefrequency response by adjusting the 3 dB point up or down to restore thefrequency response to an original, pre-irradiated performance.

Processing circuit 122 may be implemented as any one or more of amicroprocessor, a controller, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field-programmablegate array (FPGA), a system on chip (SoC) or equivalent discrete orintegrated logic circuitry. A processor may be integrated circuitry,i.e., integrated processing circuitry, and the integrated processingcircuitry may be realized as fixed hardware processing circuitry,programmable processing circuitry and/or a combination of both fixed andprogrammable processing circuitry.

Signal generation circuit 130 may output a predetermined biasing signalto biased component 126. Some examples of a bias signal may include a DCvoltage, a DC current, or some time varying signal, such as a sinusoid,square wave, impulse signal or other types of signals. A DC voltage is avoltage that is substantially constant over a time period. A DC currentis a substantially constant current. In this disclosure, substantiallyconstant means the signal is constant within measurement andmanufacturing tolerances. In some examples, the biasing signal may notnecessarily be constant, but may be otherwise known, such thatmonitoring circuit 136 can compare an actual output of biased component126 to an expected output of biased component 126 based on the knownbiasing signal. Based on the comparison of the actual output of biasedcomponent 126 to the expected output of biased component 126, processingcircuit 122 or monitoring circuit 136 can determine a compensationfactor.

Monitoring circuit 136 may receive the output signal from biasedcomponent 126. Monitoring circuit 136 may include any one or more ofamplifiers, filters, such as high pass, low pass, digital sampling, suchas analog to digital converter (ADC), or other types of signalprocessing and may be radiation hardened. In some examples monitoringcircuit 136 may include an analog switch, i.e. a multiplexor, that mayreceive output signals from a plurality of biased components throughoutsystem 100. Monitoring circuit 136 may receive commands from processingcircuit 122 and may send the processed output signal 44 to processingcircuit 122.

Processing circuit 122 may communicate with memory 124. Memory 124 maystore program instructions, which may include one or more programmodules executable by processing circuit 122. When executed byprocessing circuit 122, such program instructions may cause circuit 120to provide the functionality ascribed to herein. Memory 124 may includeany non-transitory computer-readable medium such as volatile,non-volatile, magnetic, optical, or electrical media. A non-transitorycomputer-readable medium includes but is not limited to random accessmemory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM),electrically-erasable programmable ROM (EEPROM), flash memory, or anyother computer-readable media, with the sole exception being atransitory, propagating signal. Memory 124 may also be referred to as adata storage unit.

Circuit component 128, in the example of FIG. 1, is of the same type asbiased component 126. In some examples, circuit component 128 is matchedas closely as feasible to biased component 126. For example, bothcircuit component 128 and biased component 126 may come from the samemanufacturing lot number, may be produced to the same specifications atthe same manufacturing site, and may be handled and stored under thesame conditions. Therefore, the impact of radiation on the performancecharacteristics of biased component 126, may be nearly the same as theimpact of radiation on the performance characteristics of circuitcomponent 128. Because biased component 126 and circuit component 128both operate in the same environment, the radiation exposure 15 may beassumed to be the same for both biased component 126 and circuitcomponent 128. Therefore scaling, or offsetting the output of circuitcomponent 128 (138) by the compensation factor determined above forbiased component 126 may restore the desired signal output signal 140from circuit component 128 after a performance change caused byradiation.

In the example of FIG. 1, processing circuit 122 may output a signal 142that includes a compensation factor. In some examples, signal 142 may beoutput from a digital-to-analog (D/A) circuit included with processingcircuit 122. When combined with output signal 138 from circuit component128 at junction 137, either by scaling, offset or some combination, thecompensation factor, which is based on the output signal 44 from biasedcomponent 126, may correct desired output signal 140 for any performancechange within circuit component 128 caused by radiation. As discussedabove, the compensation factor may impact any of the performancecharacteristics of circuit component 128, such as voltage response,frequency response, gain, leakage and other performance characteristics.

FIG. 2 is a block diagram illustrating an example system configured tocompensate a non-radiation hardened component based on characterizationof similar components, according to one or more techniques of thisdisclosure. Components in FIG. 2 that have reference numerals with thesame final two digits as reference numerals in FIG. 1, can be assumed tothe same function as the reference numerals in FIG. 1 with the samefinal two digits. For example, components 132 and 232 may be assumed tohave the same function, components 122 and 222 may be assumed to havethe same function, and so on. Example system 50 includes spacecraft 52and circuit 60 that may be subject to radiation exposure 15. As withFIG. 1 above, though circuit 60 is shown in an aerospace example, thetechniques may also be implemented in other applications includingmedical devices, power plants, or in any other applications that requireradiation hardened components.

Circuit 60 includes processor circuit 222 that communicates with memory224, as described above in relation to FIG. 1. Circuit 60 may alsoinclude sensing circuit 234 that receives signals from one or moresensors 232. Processing circuit 222 may receive signals from and maysend signals to other circuitry 62 and circuit component 228.

Sensing circuit 234 may include filtering, amplification, sampling andother functions to receive and process signals from sensor 232. In someexamples, sensor 232 may include a radiation sensor such as a radiationdosimeter comprising a metal oxide semiconductor field effect transistor(MOSFET). Sensor 232 may output a signal indicating an amount ofradiation received. In some examples, sensor 232 may output a signalindicating a cumulative amount of radiation received over a time period.In other examples sensing circuit 234 and/or processing circuit 222 mayreceive the signal from sensor 232 and determine a cumulative amount ofradiation received over a time period.

Circuit component 228 may be a non-radiation hardened component, similarto circuit component 128 described above in relation to FIG. 1. However,the example of circuit 60 may not include a representative circuitcomponent held under bias, as depicted by circuit 120 in FIG. 1.Instead, during a design phase or construction phase of system 50, astatistically significant sample of components of the same type ascircuit component 228 may be exposed to radiation, such as may be foundin radiation exposure 15. The performance of the sample of components,such as frequency response, amplification gain, or other performancecharacteristics, may be measured before and after exposure to radiation.In this manner, any change in the performance of the components in thesample that result from radiation exposure may be determined.

In some examples, the sample of components may be subjected to a seriesof radiation exposures and the component performance measured before andafter each exposure. In this manner, which may be referred to as testingand modeling or calibration, a component's performance may becharacterized as a result of the exposure to radiation. The results ofthe performance characterization may be recorded in a look-up table, ora formula, such as a parametric relationship between radiation exposureand a particular performance characteristic. A parametric relationship,for example, may be a linear, piecewise linear, non-linear, or someother relationship. As a result of the calibration process, theperformance characteristic for a type of component may be predictedbased on the amount of radiation received by the component. Effects forcompensation of bias and scale factor may be provided. For example, acomponent including an amplifier may decrease the amplifier gain by apercentage as the cumulative amount of radiation increases, e.g. 1%decrease for 100 millirads, 2% decrease for 200 millirads and 3% for 300millirads. In another example, a component including a filter may shiftthe 3 dB cut-off point as radiation exposure increases.

In some examples, the statistically significant sample of components maybe drawn from components that are as similar as possible to circuitcomponent 228. For example, each manufacturing lot number of aparticular type of component may be characterized separately. Similarly,a particular range of serial numbers of components may be characterized,and the component to be used in normal operation, circuit component 228,may be within the range of serial numbers, or lot number, of the testedsample. In this manner, the performance data for circuit component 228may be more accurate than just selecting a sample from a manufacturer'spart number, without taking into account manufacturing and handlingvariances.

Performance data 266 for circuit component 228 may be stored at memory224 and accessible by processing circuit 222. As noted above, processingcircuit 222 has similar function and description as processing circuit122 depicted in FIG. 1. Likewise, memory 224 has a similar descriptionto memory 124 described above. Performance data may be a look-up table,parametric relationship or other information that may be used to predictthe performance characteristics of circuit component 228 based on anamount of radiation that circuit component 228 has been exposed to overa period of time. In other words, performance data 266 may store amapping of amounts of radiation to compensation factors. Determining thecompensation factor includes retrieving, by processing circuit 222, thecompensation factor from the data storage unit based on the storedmapping.

During normal operation, a processing circuit 222 may be configured todetermine an amount of radiation received over a time period, based onthe signal from a radiation sensor, such as sensor 232. Normal operationfor a spacecraft may include operating in orbit, transiting betweenlocations, and sending and receiving communication. Circuits in normaloperation in medical settings, power plant environments and othersimilar circuits, may perform their functions as designed.

Processing circuit 222 may determine a compensation factor for circuitcomponent 228, based on the amount of radiation detected by sensingcircuit 234 and the performance data 266 retrieved from memory 224.Processing circuit 222 may compensate circuit component 228 based on theamount of radiation received and the known component performance changecaused by radiation retrieved from performance data 266, as determinedduring the modeling or calibration phase. As described above in relationto FIG. 1, in the example of FIG. 2, processing circuit 222 may output asignal 266 with the compensation factor. Junction 237 combines outputsignal 266 with signal 266. The compensation factor may correct desiredoutput signal 240 for any performance change within circuit component228 caused by radiation. Combining signals at a junction, such asjunction 237 is one example of how circuit 60 may adjust output signal266 to compensate the signal. In other examples, circuit 60 may adjustthe gain of a feedback element in a closed loop around circuit component228, or some other technique.

In other examples, compensation may not require processing circuit 222.For example, compensation may involve analog switches that are enabledbased on radiation thresholds, which incorporate addition of scalingresistors to modify the correctional summing voltages. In other words,compensation factors may use lookup tables, algorithms such as responsecharacterizations that build a polynomial curve fit, Kalman filtertechniques, or other means of adaptive software.

FIG. 3 is a block diagram illustrating an example circuit that maycompensate the input of a circuit component to achieve a desired outputsignal. The techniques illustrated by the example of circuit 100 may beapplied to either system 100 or system 50 described above in relation toFIGS. 1 and 2.

Processing circuit 322 may determine a compensation factor by any of thetechniques of this disclosure, such as retrieving performance data frommemory 324. In the example of FIG. 3, circuit component 328 receives aninput signal from other circuitry 362. Processing circuit 322 may outputa signal 308 that includes the compensation factor. Junction 304combines the compensation factor in signal 308 with the output signal302 from other circuitry 362 and outputs a modified input signal 306 tocircuit component 328. As described above, junction 304 may combinesignals by either by scaling, offset or some combination.

Compensating the input 306 to circuit component 328 may correct desiredoutput signal 340 for any performance change within circuit component328 caused by radiation. Some examples of compensating the input signalsmay include adjusting the input voltage, input current, frequencycontent or features of the input 306 to circuit component 328. In otherexamples, processing circuit 322 may also compensate the output signal338 from circuit component 328 via output signal 342 at junction 337, asdescribed above.

FIG. 4 is a block diagram illustrating an example circuit that maycompensate the signal from a non-radiation hardened circuit component tocorrect for performance changes from radiation, according to one or moretechniques of this disclosure. Circuit 420 includes another exampleconfiguration of a subset of components also included in other figureswithin this disclosure. Circuit 420 includes processing circuit 422,which is coupled to memory 424 and may receive signals from, and sendcommands to, signal generation circuit 130 and may output a signal 442to compensate the output signal 438 of circuit component 428, asdescribed above in relation to FIGS. 1-3.

In the example of FIG. 200, processing circuit 422 may also monitor theoutput signal 438A of circuit component 428. In some examples,processing circuit 422 may monitor output signal 438A via a monitoringcircuit that includes an analog switch, such as monitoring circuit 136depicted in FIG. 1 (not shown in FIG. 4). As described above in relationto FIG. 2, processing circuit 422 may receive signals indicating theamount of radiation received by circuit 420 and circuit component 428via a radiation sensor, such as sensor 32 (not shown in FIG. 4).Processing circuit 422 may further determine a compensation factor basedon both the amount of radiation received as well as analysis of outputsignal 438A.

Said another way, processing circuit 422 may receive the output signal438A of circuit component 428. In some examples, processing circuit 422may compare output signal 438A to an expected signal and determine anerror signal, where the error signal may be a difference between theoutput of the circuit component and the expected signal. In otherexamples, processing circuit 422 may perform other analysis on outputsignal 438A, and determine a compensation factor based on both the errorsignal and the amount of radiation received. In other examples,processing circuit 422, may determine the compensation factor based onthe radiation received, and further compensate output signal 438 viasignal 442 based on the error signal.

In other words, rather than relying completely on the predicted model ofthe impact on the performance characteristics of circuit component 428from radiation, processing circuit 422 may also monitor the outputsignal 438A to determine the actual impact on performance. The techniqueof monitoring the output signal 438A and adjusting any compensationfactor may also be applied to the techniques described in relation toFIG. 1, where the compensation factor is based on the output of a biasedcomponent. Monitoring output signal 438A and adjusting the compensationfactor as needed may have the advantage of more accurate compensationfor desired output signal 440, but may also add additional complicationto circuit 420.

In other examples, rather than including a second component of the sametype as circuit component 428 as a biased component, such as biasedcomponent 26, described above in relation to FIG. 1, the biasedcomponent and the operational component may be the same physicalcomponent. In one example, circuit component 428 may operate in a biasedmode at a first time and in an operational mode at a second time. Inother words, circuit component 428 may be configured to receive a biassignal from signal generation circuit 130 when configured to operate inthe biased mode at the first time. Circuit component 428 may output asignal, similar to output signal 144 from biased component 126, asdescribed above in relation to FIG. 1. Processing circuit may receivethe output signal, i.e. output signal 438A, and based on output signal438A while circuit component 428 is in the biased mode, determine acompensation factor for use in operational mode at a second time.

Processing circuit 422 may output signal 442, which includes thecompensation factor, to junction 437 to adjust output signal 438 toachieve desired output signal 440, as described above in relation toFIGS. 1-3. Similarly, processing circuit 422 may compensate the input ofcircuit component 428, as described in relation to FIG. 3 above.

FIG. 5 is a block diagram illustrating an example circuit that maycompensate a downstream component to correct for performance changesfrom radiation, according to one or more techniques of this disclosure.Circuit 520 includes another example configuration of a subset ofcomponents, which may also be included in other figures within thisdisclosure. Circuit 520 includes processing circuit 522 coupled tomemory 524, circuit component 528, downstream circuit component 550. Aswith FIGS. 1-4 above, components in FIG. 5 that have reference numeralswith the same final two digits as reference numerals in FIG. 1, can beassumed to the same function as the reference numerals in FIG. 1 withthe same final two digits. For example, components 122 and 522 may beassumed to have the same function, components 128 and 528 may be assumedto have the same function, and so on.

Downstream circuit component 550 may receive output signal 538 fromcircuit component 528. Downstream circuit component 550 may be any oneor more components that are operatively coupled to circuit component528, and receive and respond to output signal 538. In the example ofFIG. 5, processing circuit 522 may determine a compensation factor byany technique described above in relation to FIGS. 1-4. Processingcircuit 522 may output a signal 554 that includes the compensationfactor to junction 556. Junction 556 may combine signal 554 with theoutput 552 of downstream circuit component 550, similar to describedabove in relation to junction 37. As with the examples above, thecompensation factor, when applied to output signal 552, may correctoutput signal 552 to a desired signal that downstream circuit component550 may have output before the performance changed for circuit component528 based on radiation. In other words, processing circuit 522 maycompensate output signal 538 of the first circuit component, circuitcomponent 528, by adjusting an output of the second circuit component,downstream circuit component 550 to result in desired output signal 558.

In other examples, processing circuit 522 may compensate output 552 ofdownstream circuit component 550 by adjusting an input to the downstreamcircuit component 550 (not shown in FIG. 5), similar to the techniquesdescribed in relation to FIG. 3. Adjusting the input to a downstreamcircuit component may be desirable in examples in which the downstreamcircuit component is not directly connected to circuit component 528 andmay have intervening components.

FIGS. 1-5 depict some examples of techniques to compensate the output ofa component that may have been degraded or otherwise affected byradiation, such as by introducing a signal at a junction to scale oroffset the output. In other examples, a processing circuit maycompensate any intermediate input or output in the circuit. In otherexamples, a processor may not output a signal that includes acompensation factor, such as signal 142, but instead receive theuncompensated signal from the affected component and compensate theoutput using an algorithm in software.

FIG. 6 is a flow chart illustrating an example mode of operation of acircuit configured to compensate one or more non-radiation hardenedcomponents for the effects of radiation, according to one or moretechniques of this disclosure. The steps of FIG. 6 will be described interms of FIG. 1, unless otherwise noted.

A system that may be subject to radiation exposure 15 may include bothradiation hardened and non-radiation hardened components, as well asradiation shielding. In some examples, one or more performancecharacteristics of non-radiation hardened components may change whenexposed to radiation. System 100 may include circuit 120, which isconfigured to compensate one or more non-radiation hardened components28 based on an output signal from representative components of the sametype. The representative components, e.g. biased component 126, mayreceive a predetermined bias signals, such as a DC voltage, or a timevarying signal. In other words, circuit 120 may bias a first componentof a first type, e.g. biased component 126, with a predetermined biassignal, such as the output from signal generation circuit 130 (90).

A portion of circuit 120, such as processing circuit 122, may determinea first output signal 144 from biased component 126 (92). In someexamples, monitoring circuit 136 may receive output signal 144 andfilter, amplify, sample or otherwise process output signal 144 and sendthe processed signal to processing circuit 122. As described above inrelation to FIG. 1, biased component 126 is of the same type as circuitcomponent 128 and may therefore be considered a representative componentof circuit component 128.

Processing circuit 122 may determine whether there is a performancechange in biased component 126, based on output signal 144. In oneexample, processing circuit 122 may compare the first output signal 144to an expected output of the biased component 126 based on thepredetermined bias signal from signal generation circuit 130 (94). Forexample, biased component 126 may receive a DC bias voltage and mayoutput signal 144 that may be expected to be 2 V at 30 milliamps (mA).Processing circuit 122 may determine that there is a change in outputsignal 144, either an increase or decrease in voltage or current. Insome examples, processing circuit 122 may determine that there is achange in output signal 144 by comparing output signal 144 to valuesretrieved from memory 124. In other examples, processing circuit 122 maycompare output signal 144 to a reference signal generated by a radiationhardened component elsewhere in circuit 120 (not shown in FIG. 1).

As described above, processing circuit 122 may determine a compensationfactor that may restore the desired signal output from biased component126, i.e. return the output signal to 2V at 30 mA. This samecompensation factor may be applied to circuit component 128 assumingthat because biased component 126 and circuit component 128 are of thesame type and have been exposed to the same radiation, the performancechange may be the same for each.

Based on a difference between first output signal 144 and the expectedoutput signal, processing circuit 122 may compensate a second outputsignal 138 from circuit component 128, which is of the same type asbiased component 126 (96). As described above in FIGS. 1-5, processingcircuit 122 may apply the compensation factor to restore the desiredsignal output from circuit component 128 in a variety of ways.

FIG. 7 is a flow chart illustrating an example mode of operation of acircuit configured to compensate one or more non-radiation hardenedcomponents based on calibration data of the effects of radiation,according to one or more techniques of this disclosure. The steps ofFIG. 7 will be described in terms of FIG. 2, unless otherwise noted.

As described above in relation to FIG. 2, performance data 266 may bestored in memory 224. Performance data 266 may include changes in one ormore performance characteristics of circuit component 228, based oncharacterization of components similar to circuit component 228. Similarcomponents may include components of the same type from the samemanufacturing lot number. Performance data 266 may include look-uptables, parametric relationships and similar calibration data thatcharacterize the impact on one or more performance characteristics basedon an amount of radiation exposure 15.

In the example of FIG. 7, processing circuit 222 of circuit 220 mayreceive a signal indicating an amount of radiation received at aradiation sensor, such as sensor 232 (190). In some examples, the signalfrom sensor 232 may be filtered, amplified and/or sampled by sensingcircuit 234 before sending to processing circuit 222.

During normal operation, processing circuit 222 may determine an amountof radiation received by circuit 220 over a time period at the radiationsensor (192). In some examples, processing circuit 222 may receive thesignal from sensor 232 and determine a cumulative amount of radiationreceived by circuit 220 over a time period.

Processing circuit 222 may determine a compensation factor for a circuitcomponent based on the amount of radiation received over the time periodat the radiation sensor and the performance data 266 stored at memory224 (194). In the example of FIG. 7, processing circuit 222 determinesthe compensation factor during normal operation. The compensation factormay be configured to restore the desired output signal 240 from circuitcomponent 228 after a known component performance change caused byradiation as determined during calibration testing on similarcomponents.

Processing circuit 222 may compensate an output signal 238 of circuitcomponent 228, based on the compensation factor processing circuit 222may apply the compensation factor to restore the desired signal outputfrom circuit component 228 in a variety of ways, as described above inrelation to FIGS. 1-5. On example includes combining a signal 242 withoutput signal 238 at junction 237.

In one or more examples, the functions described above may beimplemented in hardware, software, firmware, or any combination thereof.For example, the various components of FIG. 3, such as receiverelectronics 315 and controller and signal generator 320 may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over, as one or more instructions or code, acomputer-readable medium and executed by a hardware-based processingunit. Computer-readable media may include computer-readable storagemedia, which corresponds to a tangible medium such as data storagemedia, or communication media including any medium that facilitatestransfer of a computer program from one place to another, e.g.,according to a communication protocol. In this manner, computer-readablemedia generally may correspond to (1) tangible computer-readable storagemedia which is non-transitory or (2) a communication medium such as asignal or carrier wave. Data storage media may be any available mediathat can be accessed by one or more computers or one or more processorsto retrieve instructions, code and/or data structures for implementationof the techniques described in this disclosure. A computer programproduct may include a computer-readable medium.

By way of example, and not limitation, such computer-readable storagemedia, such as memory 24, can comprise RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage, or other magnetic storagedevices, flash memory, or any other medium that can be used to storedesired program code in the form of instructions or data structures andthat can be accessed by a computer. Also, any connection is properlytermed a computer-readable medium. For example, if instructions aretransmitted from a website, server, or other remote source using acoaxial cable, fiber optic cable, twisted pair, digital subscriber line(DSL), or wireless technologies such as infrared, radio, and microwave,then the coaxial cable, fiber optic cable, twisted pair, DSL, orwireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. It should be understood, however,that computer-readable storage media and data storage media do notinclude connections, carrier waves, signals, or other transient media,but are instead directed to non-transient, tangible storage media. Diskand disc, as used herein, includes compact disc (CD), laser disc,optical disc, digital versatile disc (DVD), floppy disk and Blu-raydisc, where disks usually reproduce data magnetically, while discsreproduce data optically with lasers. Combinations of the above shouldalso be included within the scope of computer-readable media.

Instructions may be executed by one or more processors, such as one ormore DSPs, general purpose microprocessors, ASICs, FPGAs, or otherequivalent integrated or discrete logic circuitry. Accordingly, the term“processor,” as used herein, such as processing circuit 22, may refer toany of the foregoing structure or any other structure suitable forimplementation of the techniques described herein. In addition, in someaspects, the functionality described herein may be provided withindedicated hardware and/or software modules configured for encoding anddecoding, or incorporated in a combined codec. Also, the techniquescould be fully implemented in one or more circuits or logic elements.

The techniques of this disclosure may be implemented in a wide varietyof devices or apparatuses, including a wireless handset, an integratedcircuit (IC) or a set of ICs (e.g., a chip set). Various components,modules, or units are described in this disclosure to emphasizefunctional aspects of devices configured to perform the disclosedtechniques, but do not necessarily require realization by differenthardware units. Rather, as described above, various units may becombined in a hardware unit or provided by a collection ofinteroperative hardware units, including one or more processors asdescribed above, in conjunction with suitable software and/or firmware.

Various examples of the disclosure have been described. These and otherexamples are within the scope of the following claims.

The invention claimed is:
 1. A circuit comprising: a first component ofa first type, wherein the first component is configured to receive abias signal and output a first output signal; a second component of thefirst type; and a processing circuit, wherein the processing circuit isconfigured to: receive the first output signal; determine that there isa performance change in the first component over a period of time basedon the first output signal; in response to determining that there isperformance change in the first component, determine a compensationfactor, wherein the compensation factor is configured to compensate theoutput of the first component based on the performance change;compensate a second output signal from the second circuit componentbased on the compensation factor.
 2. The circuit of claim 1, wherein theprocessing circuit is configured to compensate the output of the secondcircuit component by adjusting an input to the second circuit component.3. The circuit of claim 1, wherein the second circuit component isoperatively coupled to a third circuit component of a second type,wherein the processing circuit is configured to compensate the output ofthe second circuit component by adjusting an input of the third circuitcomponent.
 4. The circuit of claim 1, wherein the first circuitcomponent and the second circuit component comprise a same physicalcomponent, wherein the first circuit component comprises the samephysical component when operating in a first mode, and wherein thesecond circuit component comprises the same physical component whenoperating in a second mode.
 5. The circuit of claim 4, wherein the firstcircuit component is configured to receive the bias signal and to outputthe first output signal when configured to operate in the first mode. 6.The circuit of claim 1, wherein the second circuit component isoperatively coupled to a third circuit component of a second type,wherein the processing circuit is configured to compensate the output ofthe second circuit component by adjusting an output of the third circuitcomponent.
 7. The circuit of claim 1, further comprising adigital-to-analog (D/A) circuit, wherein the processing circuit isconfigured to compensate the output of the second circuit component bycombining the output of the second circuit component with an output ofthe D/A circuit.
 8. The circuit of claim 1, wherein the compensationfactor comprises at least one of a scaling factor or an offset factor.9. The circuit of claim 1, wherein to compensate the second outputsignal from the second circuit component based on the compensationfactor restores a desired signal output from the second component. 10.The circuit of claim 9, wherein the desired signal output comprises anoriginal component performance before the performance of the secondcomponent changed.
 11. The circuit of claim 1, further comprising amonitoring circuit, wherein the monitoring circuit comprises an analogswitch.
 12. The circuit of claim 11, wherein the monitoring circuitcomprises a radiation hardened analog-to-digital converter (ADC)circuit.
 13. The circuit of claim 11, further comprising a thirdcomponent of a second type, wherein the third component is configured toreceive a second bias signal and output a third output signal andwherein the monitoring circuit is configured to receive the third outputsignal from the third component.
 14. The circuit of claim 1, wherein thebias signal is a substantially constant voltage.
 15. A methodcomprising: biasing a first component of a first type with apredetermined bias signal; determining, by a processor circuit, a firstoutput signal of the first component; comparing, by the processorcircuit, the first output signal to an expected signal of the firstcomponent based on the predetermined bias signal; and based on adifference between the first output signal and the expected signal,compensating a second output signal from a second component of the firsttype.
 16. The method of claim 15, wherein compensating the second outputsignal occurs during normal operation.
 17. The method of claim 15,wherein the first circuit component and the second circuit componentcomprise a same physical component, wherein the first circuit componentis configured to operate in a first mode at a first time, and whereinthe second circuit component is configured to operate in a second modeat a second time.
 18. The method of claim 17, wherein the first circuitcomponent is configured to receive the bias signal and to output thefirst output signal when configured to operate in the first mode at thefirst time.
 19. The method of claim 15, wherein compensating the outputsignal of the second circuit component comprises adjusting an input tothe second circuit component.
 20. The method of claim 15, wherein thecompensation factor comprises at least one of a scaling factor or anoffset factor.